Store ChangeMessage in body of commit message

Taught ChangeUpdate how to write out the ChangeMessage into
the message. Also taught ChangeNotes how to parse the
ChangeMessage out of the commit message.

Change-Id: I563eabbd848364150fdf8a5c4af5a2e1562aaefe

gerrit-server/src/test/java/com/google/gerrit/server/notedb/ChangeNotesTest.java

@@ -212,6 +212,31 @@ public class ChangeNotesTest {
     }
   }
 
+  @Test
+  public void changeMessageCommitFormatSimple() throws Exception {
+    Change c = newChange();
+    ChangeUpdate update = newUpdate(c, changeOwner);
+    update.setChangeMessage("Just a little code change.\n"
+        + "How about a new line");
+    update.commit();
+    assertEquals("refs/changes/01/1/meta", update.getRefName());
+
+    RevWalk walk = new RevWalk(repo);
+    try {
+      RevCommit commit = walk.parseCommit(update.getRevision());
+      walk.parseBody(commit);
+      assertEquals("Update patch set 1\n"
+          + "\n"
+          + "Just a little code change.\n"
+          + "How about a new line\n"
+          + "\n"
+          + "Patch-set: 1\n",
+          commit.getFullMessage());
+    } finally {
+      walk.release();
+    }
+  }
+
   @Test
   public void approvalTombstoneCommitFormat() throws Exception {
     Change c = newChange();
@@ -608,6 +633,138 @@ public class ChangeNotesTest {
     assertEquals((short) 2, psas.get(1).getValue());
   }
 
+  @Test
+  public void changeMessageOnePatchSet() throws Exception {
+    Change c = newChange();
+    ChangeUpdate update = newUpdate(c, changeOwner);
+    update.putReviewer(changeOwner.getAccount().getId(), REVIEWER);
+    update.setChangeMessage("Just a little code change.\n");
+    update.commit();
+
+    ChangeNotes notes = newNotes(c);
+    List<String> changeMessages = notes.getChangeMessages();
+    assertEquals(1, changeMessages.size());
+    assertEquals("Just a little code change.\n", changeMessages.get(0));
+  }
+
+  @Test
+  public void changeMessagesMultiplePatchSets() throws Exception {
+    Change c = newChange();
+    ChangeUpdate update = newUpdate(c, changeOwner);
+    update.putReviewer(changeOwner.getAccount().getId(), REVIEWER);
+    update.setChangeMessage("This is the change message for the first PS.");
+    update.commit();
+    PatchSet.Id ps1 = c.currentPatchSetId();
+
+    incrementPatchSet(c);
+    update = newUpdate(c, changeOwner);
+
+    update.setChangeMessage("This is the change message for the second PS.");
+    update.commit();
+    PatchSet.Id ps2 = c.currentPatchSetId();
+
+    ChangeNotes notes = newNotes(c);
+    List<String> changeMessages = notes.getChangeMessages();
+    assertEquals(2, changeMessages.size());
+    assertEquals("This is the change message for the second PS.", changeMessages.get(0));
+    assertEquals("This is the change message for the first PS.", changeMessages.get(1));
+  }
+
+  @Test
+  public void noChangeMessage() throws Exception {
+    Change c = newChange();
+    ChangeUpdate update = newUpdate(c, changeOwner);
+    update.putReviewer(changeOwner.getAccount().getId(), REVIEWER);
+    update.commit();
+
+    RevWalk walk = new RevWalk(repo);
+    try {
+      RevCommit commit = walk.parseCommit(update.getRevision());
+      walk.parseBody(commit);
+      assertEquals("Update patch set 1\n"
+          + "\n"
+          + "Patch-set: 1\n"
+          + "Reviewer: Change Owner <1@gerrit>\n",
+          commit.getFullMessage());
+    } finally {
+      walk.release();
+    }
+
+    ChangeNotes notes = newNotes(c);
+    List<String> changeMessages = notes.getChangeMessages();
+    assertEquals(0, changeMessages.size());
+  }
+
+  @Test
+  public void changeMessageWithTrailingDoubleNewline() throws Exception {
+    Change c = newChange();
+    ChangeUpdate update = newUpdate(c, changeOwner);
+    update.setChangeMessage("Testing trailing double newline\n"
+        + "\n");
+    update.commit();
+
+    RevWalk walk = new RevWalk(repo);
+    try {
+      RevCommit commit = walk.parseCommit(update.getRevision());
+      walk.parseBody(commit);
+      assertEquals("Update patch set 1\n"
+          + "\n"
+          + "Testing trailing double newline\n"
+          + "\n"
+          + "\n"
+          + "\n"
+          + "Patch-set: 1\n",
+          commit.getFullMessage());
+    } finally {
+      walk.release();
+    }
+
+    ChangeNotes notes = newNotes(c);
+    List<String> changeMessages = notes.getChangeMessages();
+    assertEquals(1, changeMessages.size());
+    assertEquals("Testing trailing double newline\n"
+        + "\n", changeMessages.get(0));
+  }
+
+  @Test
+  public void changeMessageWithMultipleParagraphs() throws Exception {
+    Change c = newChange();
+    ChangeUpdate update = newUpdate(c, changeOwner);
+    update.setChangeMessage("Testing paragraph 1\n"
+        + "\n"
+        + "Testing paragraph 2\n"
+        + "\n"
+        + "Testing paragraph 3");
+    update.commit();
+
+    RevWalk walk = new RevWalk(repo);
+    try {
+      RevCommit commit = walk.parseCommit(update.getRevision());
+      walk.parseBody(commit);
+      assertEquals("Update patch set 1\n"
+          + "\n"
+          + "Testing paragraph 1\n"
+          + "\n"
+          + "Testing paragraph 2\n"
+          + "\n"
+          + "Testing paragraph 3\n"
+          + "\n"
+          + "Patch-set: 1\n",
+          commit.getFullMessage());
+    } finally {
+      walk.release();
+    }
+
+    ChangeNotes notes = newNotes(c);
+    List<String> changeMessages = notes.getChangeMessages();
+    assertEquals(1, changeMessages.size());
+    assertEquals("Testing paragraph 1\n"
+        + "\n"
+        + "Testing paragraph 2\n"
+        + "\n"
+        + "Testing paragraph 3", changeMessages.get(0));
+  }
+
   private Change newChange() {
     Change.Id changeId = new Change.Id(1);
     Change c = new Change(